In recent years, a technique referred to as OpenFlow is proposed (see Patent Literature (PTL) 1 and Non Patent Literatures (NPL) 1 and 2). In OpenFlow, communication is deemed as an end-to-end flow, and routing control, failure recovery, load distribution, and optimization are executed for each flow. An OpenFlow switch specified in Non Patent Literature 2 includes a secure channel for communication with an OpenFlow controller serving as a control apparatus. The OpenFlow switch operates in accordance with a flow table appropriately added or rewritten by the OpenFlow controller. In the flow table, a group of: a matching rule (header fields) matched against packet headers; flow statistics information (counters); and actions defining process contents are defined for each flow (see FIG. 13).
For example, upon receiving a packet, the OpenFlow switch searches the flow table for an entry having a matching rule (see header fields in FIG. 13) that matches header information of the received packet. As a result of the search, if an entry matching the received packet is found, the OpenFlow switch updates the flow statistics information (counters) and executes process contents described in the action field of the entry on the received packet (packet transmission from a specified port, flooding, discard, or the like). On the other hand, as a result of the search, no entry matching the received packet is found, the OpenFlow switch forwards the received packet to the OpenFlow controller via the secure channel to request the OpenFlow controller to determine a packet route based on the source and destination of the received packet. Upon receiving a flow entry realizing the route, the OpenFlow switch updates the flow table. In this way, the OpenFlow switch uses an entry stored in the flow table as a process rule to forward a packet.